The overall purposes of the proposed research are 1) to study how the characteristics of amplified speech signals affect the performance and satisfaction of hearing impaired persons and 2) to identify an adequate means to identify the characteristics an individual needs in order to obtain the most acceptable assistance possible. The two principal tools we will apply in these studies are subjective judgements and articulation theory. Three different subjective methods will be used. A magnitude estimation-production method of evaluating speech intelligibility will be developed in order to produce band importance (BI) functions for continuous discourse and sets of nonsense sentences. Magnitude estimations of quality and intelligibility will be evaluated for reliability and validity with respect to inteeligibility in a format designed for clinical use. The third method is an adaptive paired comparison procedure designed to run with a high degree of efficiency under computer control. The adaptive paired comparison method will be used to 1) investigate the relative importance of the characteristics of hearing aid reproduced sound to the acceptability of a hearing aid where acceptability is defined as the best combination of intelligibility and pleasantness and 2) evaluate the intelligibility and other judged characteristics of new hearing aids or hearing aid types using juries of normal hearing persons. Articulation theory will be used in an investigation of the relationship between the functional characteristics of frequency-by-intensity regions of impaired auditory systems and the speech intelligibility provided by those regions. Also, the distribution of the proficiency factor (PF) will be measured in narrowly defined linguistic groups. Finally, hearing aid performance will be evaluated using the concept of hearing aid efficiency in which frequency response and S/N ratio effects are "controlled" by the use of the articulation index. Standard and nonstandard measures of electroacoustic performance will be related to hearing aid efficiency.